selection tool (selections are not useful yet)

src/marble_engine/board.rs

@@ -16,6 +16,20 @@ impl Pos {
 			y: self.y as f32,
 		}
 	}
+
+	pub fn min(self, other: Self) -> Self {
+		Self {
+			x: self.x.min(other.x),
+			y: self.y.min(other.y),
+		}
+	}
+
+	pub fn max(self, other: Self) -> Self {
+		Self {
+			x: self.x.max(other.x),
+			y: self.y.max(other.y),
+		}
+	}
 }
 
 impl From<(usize, usize)> for Pos {